NORTHERN MICHIGAN -- An Emmet County woman now in prison for murdering her husband has admitted responsibility in a cold case arson fire that destroyed a Petoskey restaurant more than 20 years ago, authorities say.

Two Petoskey Department of Public Safety officers interviewed Carol Kopenkoskey just prior to her late February sentencing for second-degree murder, said Chief John Calabrese.

A June 1986 fire destroyed the Country Inn Restaurant, an eatery Kopenkoskey once owned at the corner of Spring and Pleasant Streets in Petoskey.

Authorities had always considered the fire suspicious, Calabrese said, but never had enough evidence to bring charges.

That changed in late February when officers questioned Kopenkoskey over what she knew about the fire.

She admitted to pouring rubbing alcohol on the restaurant's interior walls, then setting it ablaze with a match on June 30, 1986, Calabrese said.

Kopenkoskey told officers she closed the door and left. Calabrese said the restaurant likely burned for 40 minutes to an hour without anyone noticing. It was a total loss.

Calabrese credited the officers' police work in helping bring a close to the case.

The statute of limitations will prevent prosecutors from bringing charges, however, since several decades have passed.

The admission came just before Kopenkoskey was sentenced to 18 to 35 years in prison for killing her husband, Lyle, in October 2012. She pleaded guilty to second-degree murder early this year, in Emmet County.

Interviews reviewed Carol Kopenkoskey was having an affair with a business partner and tried to withdraw $100,000 worth of insurance claims shortly after her husband died. She admitted to traveling north with that business partner, John Ernst, and throwing the revolver involved in the murder off the Mackinac Bridge, police earlier said.

Ernst faces six counts of perjury and one count of being an accessory after the fact. He was charged in early February.